[gradsusr] Conditional handling of terms

[Stefan Gofferje]

Hi,

I'm just working on plotting a few new indices and I am wondering if and
how the conditional handling of terms is possible in grads somehow.

E.g.: SWEAT index...

The definition says
SWEAT= 12(850Td) + 20(TT - 49) + 2(V850) + (V500) + 125(sin(dd500 -
dd850) + 0.2)

*If TT less than 49, then that term of the equation is set to zero
*If any term is negative then that term is set to zero
*Winds must be veering with height or that term is set to zero

How would I do something like this. The only thing I could think of
would be, going through the grid with two while loops, calculating the
values with a couple of "if" clauses, then output them to a new grid and
plot this new grid. But that seems a bit overkill, doesn't it? :)

-Stefan

-- 
Suomen Sääkeskus - Hyvä sää on makuasia

Stefan Gofferje
Haukantie 2 B 5
FIN-37600 Valkeakoski
GSM:       +358 (41) 7290730

http://www.saakeskus.fi/
stefan at saakeskus.fi


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